Cooling system



COOLING SYSTEM Filed May 3l, 1933 @im Z i i Y 4l' IPA/5yd,

Patented Mar. 14, 1939 UNITED STATES APlvrlazN'r OFFICE COOLING SYSTEM Charles S. Lcopo Elkins Park, Pa.

Application May 3l, 1933, Serial No. 673,602

4 Claims.

This invention relates to a cooling system and more particularly to an arrangement of such system whereby an economy of size and capacity of apparatus is effected. More specifically it relates to an air conditioning system in which particularly the size of the refrigerating compressor is reduced.

In the present units of the type designed for the cooling of air for air conditioning purposes, it is customary to design the complete refrigerating plant of such capacity to meet the peak de- L mand and therefore for the. major portion of the day the plants are operating at less than peak capacity and are idlel for a large portion of the twenty-four hours. In the usual'type of design it is necessary to have electrical service supplied of a size which will supply the compressor for peak demands and also to have water connections to and from the condensers which are large enough to supply such demands.- 'Ihls has been a great deterrent to the installation of such units in oillce buildings and homes where the cost of special electric service and water connections and even the lack of availability oi water in large quantities are -serious items. Because of these objections these units are usually designed with very little spare capacity for the peaks and therefore cannot operate to rapidly produce proper cooling effect at the start of a conditioning pe-v riod or to take care of short unusual demands. Furthermore, in the average ofiice, for example, the maximum period of use is eight hours per day and usually not at peak capacity and so that the equipment is idle for the other two-thirds In my Patent No. 2,056,970, dated October 13, 1936, I have described and claimed ,a system in which ice is stored during oi-peak periods to supply peak demands so that a small refrigerating plant is able by substantially continuous 'operation to provide refrigerating effect at all times. 'I'he storage of ice is highly advantageous inasmuch as its high latent heat of fusion provides for the storage of a very considerable refrigerating effect in a small space.

The storage of ice is much more effective than the storage of cold water since the space required for the storage of cold water is usually prohibitive. Furthermore, it is highly desirable particularly in the design of unit coolers to provide for a very low dew point which entails bringing the airwater mixture to a low temperature.

Some of the principles disclosed in my prior patent are used in the present one. Specifically,. however, the arrangement of the prior patent was designed for the cooling of water which was then used for the cooling of air to be conditioned. Such a unit is highly desirable where a very considerable space is to be supplied with conditioned air but is somewhat bulky and unnecessary and more costly for incorporation in a single air conditioning unit such as might be enclosed in one cabinet for use in oillces or the like.

Specifically, instead of having the stored ice cool water and then having the water cool the air in heat interchange apparatus external to the ice storage enclosure, in accordance with the present invention the air is blown directly over the ice and exposed surface of the evaporator and water which is in circulation over the ice and any additional surface, thus providing a direct and simple means of heat transfer.

Subsidiary-purposes of the invention particularly relating to the control of ice building upon refrigerating surfaces, and other details of construction involving, for example, controls of pumps for the refrigerating apparatus, will be apparent from the following description read in conjunction with the accompanying drawing in which:

Fig. 1 is a diagrammatic view of a preferred embodiment of the invention, certain of the parts being shown broken away to illustrate interior construction; and

Fig, 2 is a vertical section through the same.

In Figs. 1 and 2 there is illustrated at 2 a heat insulated cabinet of suitable type into which air is drawn either from the room to be supplied with conditioned air or from the exterior of the building, or both, as may be desired, through heat v exchange conduits 4 which may take the form of a plurality of metal tubes with or without extended surfaces so that heat transfer will take place. If desired. such heat exchange arrangement may be omitted, the air being directly led to the intake of a motor driven fan 6 which discharges air through chamber 8 and causes it to pass upwardly between refrigerating coils I0 and thence out at the top of the cabinet through a suitable screen or grid arrangement after rst passing in heat exchange relationship with the conduits 4 if such conduits are provided. The coils l0 are preferably provided with ns 9 extending longitudinally and/or transversely to afford extended surfaces to more eiectively cool the air and to aid in the building of ice. 'I'he guidance of thel air to a position below refrigerating coils I0 is effected by the use of suitable be provided at the top of the cabinet coils indicated at I3 which in the winter may be used for heating the air, the refrigerating apparatus being at such times shut down although, as will be clear hereafter, a circulationof water in thin lms over the refrigerating coils may be maintained for the purpose of humidifying the air.

A tank indicated at I6 is provided in the bottom of the cabinet. Water from this tank is supplied by a pump I6 driven by a motor I2 through a pipe 2li terminating in a header which delivers the water to distributing trays 22 from which the water flows downwardly over the refrigerating coils Iii or ice formed thereon back to the tank I4. Sprays may be additionally provided if desired.

Also preferably within the cabinet there is located a motor driven compressor indicated conventionally at 26 together with the other elements of the usual refrigerating plant including a condenser 2li and a cooler indicated at 3G for the space in the cabinet which contains the compressor. Both the compressor and cooler 3@ may be supplied with cooling water from the usual means, or cooling by air may be used. The compressor discharges the hot refrigerant gas under pressure through pipe 58 to the condenser 28 where it is cooled and condensed to a liquid and continues as a liquid through pipe GII to expansion valve 62, where it is expanded to the low pressure side of the refrigerating system. The condenser water is admitted to the cooler 3E and condenser 28 through a pipe E6 and is wasted through pipe 56. The refrigerating plant is lprovided with the usual conventional controls for insuring a proper action and maintenance of the coils I0 below the freezing point of the water. Several cooling units maybe supplied from a single refrigerant compressor. In such case, if the water pump of any unit stops, the expansion valve of the corresponding coil I@ should be closed automatically through a suitable control.

A switch indicated at 32 controls the operation of the refrigerant compressor and the pump motor I8 in addition to the other conventional controls. This switch is operated by'vertical movements of a rod 36 provided with two stops 3S and 38 between which there moves a float4. Whenv the oat 40 rises because of the presence of suillcient liquid within the tank I4 the switch 32 startsthe compressor so that the coils I0 are cooled below the freezing point. On the other hand, if the liquid level drops to such extent that it will pull the rod 34 downwardly the switch will be opened and the compressor stopped.

Since the operation of the apparatus may be such and is desirably such that the air is cooled below its dew point, if the humidity is high there may be a considerable accumulation of water within the apparatus. Accordingly, an overflow 42 is provided which may discharge directly into sewer connections, or if this is impractical into a tank 44 in which there is located a float 46 serving to operate a switch 48. If the level within the tank 44 becomes too high the switch 48 is opened thereby stopping the blower 6 so as to prevent the accumulation of too much water in the system. Under these conditions the excess water may be drawn olf through a valve 50 from the main tank I4 and through a valve 52 from theauxiliary overflow tank 44.

The operation of the device will now be clear. Initially the tank I 4 is full of water and the blower 6 stopped, this blower being subject to auxiliary control so that it will not operate during araches standby periods such as, for example, week-ends. or nights, in the case of an omce installation. By supplying power to the refrigerating system the oat switch 32 will start the motor I8 and the compressor 28 and water will be circulated over the refrigerating coils I0 so that there will be -built up thereon a coating of ice as indicated at 24. The capacity of the tank I4 is such that when the level drops to such extent as to cause the iloat 4U to open the switch 32 and stop the compressor, the accumulating ice on the coils Io will be of such amount that there will remain passages therethrough through which air may pass. As soon as a desired quantity of ice is accumulated the blower 6 may be started whereupon the air conditioning effect will continue automatically subject to the control of the blower by c thermostat. By the heat exchange arrangement at t the incoming air is slightly cooled before reaching the blower while the outgoing air is slightly warm as will usually be desirable. If the total heat of the entering air is high a condition may be reached under which the melting of the ice from the coils III takes place more rapidly than the formation oi' ice thereon. `The water trickling over the ice and between ice formations tends to wash the upwardly flowing air thereby removing from it dust and absorbable gases and aiding the heat transfer. When there arrives a period such that the air is no longer warm or the fan is not in operation, as, for example, after ofiice hours or during a cool day, the ice will build up on the coils I0 until eventually the level in tank I4 is reduced to such extent that the switch 32 will stop the compressor and pump. If the blower continues to operate there will 4then eventually be sufficient ice melted to resupply the tank to such extent that the refrigerant compressor will be restarted.

The preferred design o1' the apparatus is such that the compressor under ordinary conditions will operate the greater part of the time being insufficient however to supply independently the peak demands. The peak demands are taken care of by the melting of the accumulated ice on the coils IIJ. It will thus be seen that there is provided an apparatus which can effectively take care of the peaks even though the refrigerating plant is too small to directly take care of the peak demands. Economy of operation is thus obtained with respect to both the electrical requirements and the requirements oi ample cooling water for the condenser. The blower is preferably controlled by a suitable thermostat or hygrostat located within the space supplied by the apparatus.

Reference to my prior patent may be made to illustrate various modes ofcontrolling the building up of the ice upon refrigerating surfaces. The various arrangements described in that patent are applicable to an arrangement in which melting down is effected by either direct or indirect contact of air with the ice.

It will be seen that in accordance with the invention unusual peaks are met by increased melting of ice and will not be reiiected directly in the rate o! refrigeration but merely in the total hours of operation of the refrigerating system. Assuming a peakV demand of eight hours in a twentyfour hour period the economies effected involve a reduction of condenser water piping to one-third the size which would be required for systems designed to meet the peak, a reduction o! the electric service demanded by the motor and a lower cost per unit for electrical energy-wherever energy is charged for on the basis of a standby and consumption charge.

As pointed out above, both heating and humidifying can be embodied in the apparatus illustrated by the provision of heating coils I3 and the operation of the pump I6 without the operation of the refrigerating plant.

It will be clear that numerous variations in the embodiment of the invention may be made without departing from the scope thereof as defined in the following claims,

What I claim and desire to protect by Letters Patent is:

1. In combination, means providing a surface cooled below the freezing point of a liquid and arranged to carry a coating of frozen liquid, means for passing liquid in the form of a nlm in heat interchange with said surface to build up a coating thereon, means for interrupting the flow of liquid when the coatings are built up to a predetermined extent, and means for passing a gas in contact with said coating.

2. In combination, means providing a surface cooled below the freezing point of a liquid and arranged to carry a coating of frozen liquid, a supply of liquid, means for recirculating liquid from the supply, in heat interchange with the surface, and back to the supply, to thereby build up a coating on the surface, means for interrupt- .ing the circulation of liquid when the amount of liquid in the supply is reduced to a predetermined degree, means for renewing circulation when the amount of liquid in the supply is again increased, and meansdor passing a gas in contact with said coating. Y

3. In combination, means providing a surface cooled bel'ow the freezing point of a liquid and` arranged to carry a coating of frozen liquid, a supply of liquid, means for recirculating liquid from the supply, in heat interchange with the surface, and back to the supply, to thereby build up a coating on the surface, means for passing a gas in contact with said coating, and means forinterrupting the passage of' gas when the amount frozen coating of said liquid, but insufl-cient `during periods of higher heat interchange between the gas and surface to prevent melting. of the coating, so that when the rate of heat interchange between the gas and coating is higher than the rate of heat interchange between the coating and the surface the load isr taken care of by the accumulated frozen liquid.

CHARLES S. LEOPOLD. 

